A method for monitoring a secondary-air system in combination with the exhaust-gas system of a motor vehicle is described by an environmental authority in California, i.e. CARB. In the known method, the secondary-air pump is connected for a short time and the control stroke of the lambda-control circuit caused thereby is observed. If this control stroke exceeds a threshold value, it can be assumed that the secondary-air pump is supplying a sufficiently large stream of air.